[R] merge with origin information in new variable names

[Phil Spector]

Eric -
     As others have said, you should change the names of the variables
in the data frames before you merge them.  Here's one implementation
of that idea:

    DF.wave.1 <- data.frame(id=1:10,var.A=sample(letters[1:4],10,TRUE))
    DF.wave.2 <- data.frame(id=1:10,var.M=sample(letters[5:8],10,TRUE))
    DF.wave.3 <- data.frame(id=1:10,var.A=sample(letters[5:8],10,TRUE))

    nms = paste('wave',1:3,sep='.')
    dfs = list(DF.wave.1,DF.wave.2,DF.wave.3)
    names(dfs) = nms

    changenm = function(nm){
        df = dfs[[nm]]
        wh = names(df) != 'id'
        names(df)[wh] = paste(names(df)[wh],nm,sep='.')
        df
    }

    Reduce(function(x,y)merge(x,y,by='id'),lapply(names(dfs),changenm))

 					- Phil Spector
 					 Statistical Computing Facility
 					 Department of Statistics
 					 UC Berkeley
 					 spector at stat.berkeley.edu




On Mon, 25 Apr 2011, Eric Fail wrote:

> Is there anyone out there who can suggest a way to solve this problem?
>
> Thanks,
> Esben
>
> On Sun, Apr 24, 2011 at 8:53 PM, Jeff Newmiller
> <jdnewmil at dcn.davis.ca.us> wrote:
>> Merge only lets you combine two tables at a time, but it does have a
>> "suffix" argument that is intended to address your concern, but only for
>> variable names that would conflict.
>>
>> In your example, the id variables are all sequenced exactly the same, so you
>> could actually use cbind rather than merge.
>>
>> However, whether you use merge or cbind, I think the most direct route to
>> your desired result is to rename the data columns before you combine them,
>> using the names function on the left hand side of an assignment with a
>> vector of new names on the right.
>> ---------------------------------------------------------------------------
>> Jeff Newmiller The ..... ..... Go Live...
>> DCN:<jdnewmil at dcn.davis.ca.us> Basics: ##.#. ##.#. Live Go...
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>> ---------------------------------------------------------------------------
>> Sent from my phone. Please excuse my brevity.
>>
>> Eric Fail <eric.fail at gmx.com> wrote:
>>>
>>> Dear R-list,
>>>
>>> Here is my simple question,
>>>
>>> I have n data frames that I would like to merge, but I can't figure out
>>> how to add information about the origin of the variable(s).
>>>
>>> Here is my problem,
>>>
>>> DF.wave.1 <- data.frame(id=1:10,var.A=sample(letters[1:4],10,TRUE))
>>> DF.wave.2 <- data.frame(id=1:10,var.M=sample(letters[5:8],10,TRUE))
>>> DF.wave.3 <- data.frame(id=1:10,var.A=sample(letters[5:8],10,TRUE))
>>>
>>> Now; I would like to merge the three dataframes into one, but append a
>>> suffix to the individual variables names about thir origin.
>>>
>>> DF.wave.all <- merge(DF.wave.1,DF.wave.2,DF.wave.3,by="id", [what to do
>>> here])
>>>
>>> In other words, I would like it to loook like this.
>>>
>>> DF.wave.all
>>>    id var.A.wave.1 var.M.wave.2 var.A.wave.3
>>> 1   1            c            h            j
>>> 2   2            c            e            j
>>> 3   3            c            g            k
>>> 4   4            c            e            j
>>> 5   5            c            g            i
>>> 6   6            d            e            k
>>> 7   7            c            h            k
>>> 8   8            b            g            j
>>> 9   9            b            f            i
>>> 10 10            d            h            i
>>>
>>>
>>> Is there a command I can use directly in merge? 'suffixes' isn't really
>>> handy here.
>>>
>>> Thanks,
>>> Eric
>>> ________________________________
>>> R-help at r-project.org mailing list
>>> https://stat.ethz.ch/mailman/listinfo/r-help
>>> PLEASE do read the posting guide
>>> http://www.R-project.org/posting-guide.html and provide commented, minimal,
>>> self-contained, reproducible code.
>>
>
> ______________________________________________
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> PLEASE do read the posting guide http://www.R-project.org/posting-guide.html
> and provide commented, minimal, self-contained, reproducible code.
>